Insulating window incorporating photovoltaic cells and a pressure equalization system

ABSTRACT

A heat insulating window comprises a pair of outer glass panes, held apart by a spacing member and surrounded by a frame enclosing at least one photovoltaic cell. In a preferred embodiment a conduit system providing gas communication to the air space between the glass panes includes a desiccant.

FIELD OF THE INVENTION

The present invention relates generally to window structures, and moreparticularly to window structures comprising photovoltaic panels.

BACKGROUND

Windows or glass areas are a significant weakness in the heat insulationschemes for buildings in hot or cold climates. A basic insulating windowthat is well-known is constructed from two panes of glass within a rigidframe. The air space between the panes provides heat insulation.

Photovoltaic units, when disposed between the two panes, heat the airentrapped within the insulating glass unit, which causes the seal tofail prematurely. U.S. Pat. No. 4,137,098 to Gillard disclosesphotovoltaic cells enclosed between two panes of glass of a windowhousing that is cooled by a forced air system. U.S. Pat. No. 5,128,181to Kunert discloses photovoltaic cells enclosed between two panes ofglass of a window housing in which excess solar radiation is dissipatedoutwardly by convection. U.S. Pat. No. 5,221,363 to Gillard disclosesphotovoltaic cells enclosed between two panes of glass of a windowhousing having valves so that excess heat may be removed by convection.However, if the entrapped air is vented, when the window cools and airreenters the unit, condensation may occur which impairs the transparencyof the window unit.

Therefore there is a need in the art for an insulating glass unit windowstructure, which includes a photovoltaic cell and mitigates thedifficulties posed by the prior art.

SUMMARY OF THE INVENTION

The present invention is directed to a pressure equalized heatinsulation window comprising photovoltaic cells. Therefore, in oneaspect, the invention comprises a heat insulation window comprising:

-   -   (a) a pair of glass panes defining an air space therebetween;    -   (b) a spacing member disposed between said glass panes which        maintain the panes in a spaced-apart relationship;    -   (c) at least one photovoltaic cell disposed between said glass        panes; and    -   (d) a frame surrounding a perimeter of the window, wherein the        frame comprising a conduit means for providing gas communication        through the frame to the air space.

In one embodiment the conduit means comprises a desiccant.

In other embodiments the frame encloses an interior space and comprisesan access means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of an exemplary embodimentwith reference to the accompanying simplified, diagrammatic,not-to-scale drawings. In the drawings:

FIG. 1 is a perspective view of a heat insulation window enclosingphotovoltaic cells and a diagrammatic representation of electricalconnections;

FIG. 2 is a cross-sectional view of the window of FIG. 1 (photovoltaiccells not shown), showing the interior space enclosed by the windowframe and access means; and

FIG. 3 is a cross-section of the embodiment of FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides for an energy efficient, heat insulatingwindow design. When describing the present invention, all terms notdefined herein have their common art-recognized meanings.

FIG. 1 shows a perspective view of photovoltaic cells (2) mounted on theinner surface of outer glass pane (12) and a diagrammatic representationof electrical connections (4).

FIGS. 2 and 3 show the heat insulation window with a pressureequalization system as described in co-owned Canadian Patent Application2,507,108, the contents of which are herein incorporated by reference.

FIG. 2 shows a view of a window unit comprising dual glass panes (10,12) and a frame (14).

FIG. 3 shows cross-sections of the glass panes (10, 12) spaced apart bya spacer (16) and held together by the frame (14).

The frame comprises an outer channel member (18), an inner channelmember (20) and dual intermediate web members (22) which join the innerand outer channel members. The inner channel member may include aninstallation flange (24) which projects outwardly and will abut a windowjamb (not shown) when installed into a wall frame. A removable desiccantconcealing member (26) is attached to the inner channel member (20)opposite the installation flange (24) which serves to retain the glassunit but does not serve any other structural function. The desiccantconcealing member (26) is tube-shaped defining a single elongate channel(28). One edge of the channel defines a first lip (30) while the otheredge of the channel defines a second lip (32). The two lips (30, 32)mate with corresponding grooves (31, 33) formed in the inner channelmember (20). The glass planes are positioned and retained by resilientseals (34, 36, 38). Seal (34) is attached to the outer channel member(18) while seal (36) is attached to the inner channel member (20). Airseal (38) is attached to the desiccant concealing member (26). The sealsare preferably formed from a material having low thermal conductivityand relatively impervious to moisture, such as neoprene, EPDM orsilicone rubber.

In a preferred embodiment, a dual desiccant system is employed. Thespacer (16) is a hollow rectangular member which is filled with asuitable desiccant (40). The spacer defines pores which allow air tocirculate between the air space between the glass panes (10, 12) and theinterior volume of the spacer (16) which contains the desiccant. Aswell, a small conduit (42) connects the interior space of the spacer toa sealed tube (44) within the desiccant concealing member (26) which isfilled with desiccant (40). The sealed tube (40) has a cap (46) whichreceives the conduit (42) thereby providing gas communication betweenthe spacer interior volume and the desiccant tube (44).

As is apparent, the desiccant concealing member (26) may be removed fromthe frame (14) by disengaging the lips (30, 32) from the inner channelmember (20), thereby exposing the desiccant tube (44). The desiccanttube (44) can then be easily disconnected from the conduit (44) andreplaced with a fresh desiccant tube if necessary. In one alternativeembodiment, the desiccant in the desiccant tube may be different fromthe desiccant contained in the spacer and has a higher affinity forwater than the desiccant in the spacer. As will be appreciated by thoseskilled in the art, air which is drawn into the air space must passthrough the replaceable desiccant tube, thereby preserving the dryatmosphere within the window unit.

Desiccant tubes (44) may be placed in one, two, three or all fourdesiccant concealing (20) members (26) in any orientation.

The outer, intermediate and inner channel members which comprise theframe (14) may be formed from a thermoplastic material having lowthermal conductivity such as polyvinylchloride or polyamide.Alternatively, the inner and outer channel members may be metallicmembers such as aluminum while the intermediate member is non-metallic,thereby avoiding a thermal bridge between the two. The desiccantconcealing members may be any suitable material such as a metal or aplastic, and is preferably resilient to facilitate its installation andremoval from the inner channel member.

A solar cell, or photovoltaic cell (2), is a semiconductor deviceconsisting of a large-area p-n junction diode, which, in the presence ofsunlight is capable of generating usable electrical energy. Any suitabletype photovoltaic cell (2) can be used in the window described herein.For example, silicon, calcium sulfide, gallium arsenide and other typesof cells are suitable. The cells can be of any desired configurationsuch as square, circular.

The photovoltaic cells may be any suitable cell, such as crystallinewafers, or thin film cells. As an alternative to using crystallinephotovoltaic cell wafers, photovoltaic laminated glass can also beproduced using thin-film solar photovoltaic (PV) cells. The fabricationof a thin-film solar cell involves depositing very thin, consecutivelayers of atoms, molecules, or ions of semiconductor material (such asamorphous silicon, copper indium diselenide, or cadmium telluride) on alow-cost substrate, such as glass, metal, or plastic. Thin-film cellshave certain advantages over crystalline solar cell wafer technologies.They use less material and the cell's active area is usually only 1 to10 microns thick, whereas conventional wafers are as much as 200 to 400microns thick. Thin-film cells are also usually amenable to large-areafabrication (more than 1 m²) and are suitable for automated, continuousproduction, arraying, and packaging. They can also be deposited onflexible substrate materials.

In one embodiment, the photovoltaic cells (2) are disposed between thetwo glass panes of glass (10, 12) as a photovoltaic laminate, with thephotovoltaic cells laminated between two glass panels. In conventionallaminated glass products a sheet of glass is bonded to a layer ofpolymer adhesive film, and a further sheet or layer of material isbonded to the other side of the adhesive film layer, so that theadhesive film is sandwiched between two outer layers. A number ofmethods for producing such laminates are known, for example, see U.S.Pat. Nos. 5,268,049; 5,118,371; 4,724,023; 4,234,533; and 4,125,669.Laminated glass has been generally manufactured by a process wherein astack of at least two sheets of glass having a plastic film called anintermediate film or laminating film, typically a plasticized polyvinylbutylal (PVB) film, is sandwiched between each pair of adjacent sheetsof glass which is subjected to evacuation, pressing and heating.

The photovoltaic cells (2) are usually electrically connected (4)together in a series circuit to achieve desired voltage, and a pluralityof series circuits of photovoltaic cells can then be connected inparallel, as desired. The electrical energy can then be fed by electriclines (4) from + and − terminals to a power control or other suitabledistribution device (6). Such conventional electrical circuitry, wouldpreferably include an isolator, to a main power bus. As well known inthe art, an inverter would be used to produce alternating current (AC)from direct current (DC) produced by the photovoltaic cells. Preferably,a plurality of photovoltaic cells are grouped in parallel to raise thevoltage and each group is provided with a three pole disconnect DCswitch and an inverter, the AC current then passing to a 208 voltdistribution panel.

As will be apparent to those skilled in the art, various modifications,adaptations and variations of the foregoing specific disclosure can bemade without departing from the scope of the invention claimed herein.The various features and elements of the described invention may becombined in a manner different from the combinations described orclaimed herein without departing from the scope of the invention.

1. A heat insulation window comprising: (a) a pair of glass panesdefining an interior air space therebetween; (b) a spacing memberdisposed between said glass panes which maintain the panes in aspaced-apart relationship; (c) at least one photovoltaic cell disposedbetween said glass panes; and (d) a frame surrounding a perimeter of thewindow, wherein the frame comprises a conduit means for providing gascommunication through the frame to the air space.
 2. The heat insulationwindow of claim 1 wherein said conduit means comprises a desiccant. 3.The heat insulation window of claims 1 or 2 wherein said at least onephotovoltaic cell is laminated to one of said glass panes.
 4. The heatinsulation window of claims 1-3 wherein said frame encloses an interiorspace and comprises an access means through said frame to said interiorspace.
 5. The heat insulation window of claim 1 or 2 wherein the spacingmember defines an internal volume in gas communication with the airspace between the glass panes, and further comprising a dessicantdisposed within the internal volume.
 6. The heat insulation window ofclaim 5 wherein said at least one photovoltaic cell is electricallyconnected to a three pole disconnect direct current switch and aninverter.
 7. A heat insulation window comprising: (a) a pair of glasspanes defining an air space therebetween and having a photovoltaic celldisposed within the airspace; (b) a spacing member disposed between theglass panes which maintain the panes in a spaced-apart relationship, thespacing member being hollow and defining openings permitting gascommunication between the air space and the interior volume of thespacing member; (c) a desiccant material contained within the spacingmember; and (d) a frame surrounding a perimeter of the window, whereinthe frame comprises: (i) at least one desiccant concealing member whichis hollow and detachable from the frame; ii) a desiccant cartridgeremovably disposed within the desiccant concealing member and (iii)conduit means for providing gas communication between the air space andthe desiccant cartridge.
 8. The window of claim 7 wherein the conduitmeans provides gas communication between the interior volume of thespacing member and the desiccant cartridge.
 9. The window of claim 7wherein the desiccant cartridge comprises an elongated cylindrical tube.10. The window of claim 7 wherein the desiccant concealing member iselongated and has a substantially U-shaped cross-sectional profile. 11.The window of claim 10 wherein the cross-sectional profile comprises twolinear segments joining at a substantially right angle.
 12. The windowof claim 7 wherein the frame comprises an outer channel member, an innerchannel member, a web member disposed between the outer and innerchannel members, wherein the desiccant concealing member is detachablyconnected to the inner channel member.
 13. The window of claim 10wherein the desiccant concealing member is comprised of a resilientmaterial and comprises a first lip and a second lip which each engage anundercut groove in the inner channel member.